我有一组PHP数组，我正在尝试检索这些细节和回显。 但是我收到错误，例如Warning: Invalid argument supplied for foreach().如何纠正此类错误的出现？当我回显所有用户的所有蛋糕时，会出现此问题。
到目前为止，我已经尝试从代码中消除可能的错误，并且还使用了验证语句，例如 if empty 然后执行此操作，但是问题仍然存在。
<?php
//USERS ARRAYS
$users = array();
$users["john"] = array(
"first name" => "John",
"last name" => "Smith",
"address" => "London");
$users["jade"] = array(
"first name" => "Jade",
"last name" => "Anthony",
"address" => "Essex");
$users["clement"] = array(
"first name" => "Clement",
"last name" => "Smith",
"address" => "Essex");
//CAKES ARRAY
$cakes = array();
$cakes = array(
"john" => array(
"Chocolate Cake" => array(
"ingredients" => "chocolate, flour, eggs",
"cooking time" => "20 minutes"),
),
"jade" => array(
"Lemon Cheesecake" => array(
"ingredients" => "lemons, flour, eggs",
"cooking time" => "30 minutes")),
"clement" => NULL,
);
?>
<?php $user_name = 'john';?>
<h1>Name</h1>
<p><?php echo $users["first name"]; ?></p>
<h1>Cakes Made</h1>
<?php
foreach($cakes[$user_name] as $key => $val)
{ echo $key . " <strong>Ingredients: </strong>" . $val["ingredients"] . "<br>"; }
?>
<h1>All cakes from all users</h1>
<?php foreach($cakes as $cake) { ?>
<?php if(is_array($cake)) {
foreach($cake as $cakemade => $newval)
if(empty($cakemade)) { echo "";} else
{ echo $cakemade . "<strong>" . $newval['ingredients'] ."</strong> <br>"; }
?>
<?php }} ?>
欢迎您的意见。:)
编辑：为了清楚起见，代码错误与代码的第二部分有关，其中显示所有用户的所有蛋糕。
您可以测试是否设置了 want use in foreach 中的变量
if(isset($cakes[$user_name]) && count($cakes[$user_name]) > 0)
foreach($cakes[$user_name] as $key => $val) {}
缺少keys的 " s 。您的阵列应该是 -
$cakes = array(
"john" => array(
"Chocolate Cake" => array(
"ingredients" => "chocolate, flour, eggs",
"cooking time" => "20 minutes"),
)
"jade" => array(
"Lemon Cheesecake" => array(
"ingredients" => "lemons, flour, eggs",
"cooking time" => "30 minutes"),
"clement" => NULL,
);
if(is_array($variable) && count($variable) > 0) {
foreach($variable as $key => $value) {
//Your code
}
)
粘贴的代码中有许多语法错误。 还可以使用 is_array() 来检查数组。此外，您还定义了$username = "john"并传递了带有$user_name尝试
<?php
//USERS ARRAYS
$users = array();
$users["john"] = array(
"first name" => "John",
"last name" => "Smith",
"address" => "London");
$users["jade"] = array(
"first name" => "Jade",
"last name" => "Anthony",
"address" => "Essex");
$users["clement"] = array(
"first name" => "Clement",
"last name" => "Smith",
"address" => "Essex");
//CAKES ARRAY
$cakes = array();
$cakes = array(
"john" => array(
"Chocolate Cake" => array(
"ingredients" => "chocolate, flour, eggs",
"cooking time" => "20 minutes"),
),
"jade" => array(
"Lemon Cheesecake" => array(
"ingredients" => "lemons, flour, eggs",
"cooking time" => "30 minutes")),
"clement" => NULL,
);
?>
<?php $user_name = 'john';?>
<h1>Name</h1>
<p><?php echo $users["first name"]; ?></p>
<h1>Cakes Made</h1>
<?php
foreach($cakes[$user_name] as $key => $val)
{ echo $key . " <strong>Ingredients: </strong>" . $val["ingredients"] . "<br>"; }
?>
<h1>All cakes from all users</h1>
<?php foreach($cakes as $cake) { ?>
<?php if(is_array($cake)) {
foreach($cake as $cakemade => $newval)
if(empty($cakemade)) { echo "";} else
{ echo $cakemade . "<strong>" . $newval['ingredients'] ."</strong> <br>"; }
?>
<?php }} ?>
可能最好的方法是检查变量是否为数组，然后检查它是否为空。正如您已经明确指出的那样，如果变量是数组并且它不为空，那么您应该浪费处理器时间来迭代数组。
所以代码看起来像这样：
if(!empty($var) && is_array($var)) {
foreach($var as $key => $value) {
echo $key . ' => ' . $value;
}
}